1. Field of the Invention
This invention relates to an image forming device, an image formation operation correction method, and an image formation operation correcting program in which a correction pattern is formed on an intermediate transfer body in advance of image formation and an image formation operation is corrected by detecting the correction pattern.
2. Description of the Related Art
In a conventional image forming device, image formation operation is suspended temporarily and various kinds of correction operation in image formation are performed. For example, the amount of color gap in image formation is corrected using an alignment correction pattern.
In the image forming device of this type, image formation operation is temporarily interrupted, and an additional stopping time for performing the various kinds of correction operation is needed before the image formation operation is resumed. Then, there is an increasing demand for reducing the stopping time for performing the various kinds of correction operation as much as possible, in order to accelerate the image formation.
Japanese Laid-Open Patent Application No. 2005-091901 discloses an image formation operation correcting method. In the case of this image formation operation correcting method, in order to reduce the stopping time, a plurality of correction patterns for various kinds of correction operation are continuously formed on an intermediate transfer body, and the plurality of correction patterns are detected continuously by sensors, without suspending the image formation operation.
According to the method of Japanese Laid-Open Patent Application No. 2005-091901, the plurality of correction patterns which should be detected, including a process control pattern, a blade curling prevention pattern, and an alignment correction pattern, are formed in proximity to each other on the intermediate transfer body. It is necessary that the correction patterns formed thereon are distinguished from each other and detected correctly.
However, in the method of Japanese Laid-Open Patent Application No. 2005-091901, fixed start timing for starting the detection of the correction patterns on the intermediate transfer body by using the sensors is set up beforehand. If a change in any of various image formation parameters, including image formation speed, image formation distance, and so on, occurs, the actual timing of the start of detection of the correction patterns by the sensors is shifted from the fixed start timing. Therefore, it is difficult to correctly detect the correction patterns by the sensors when a change in any of the image formation parameters occurs.
Namely, the plurality of correction patterns are formed continuously on the intermediate transfer body, and inevitably the difference between the blade curling prevention pattern and the alignment correction pattern is very small. For this reason, if the mounting positions of the sensors are shifted a little or the mounting positions of the sensors are adjusted finely, or if the image formation speed increases, the problem that the blade curling prevention pattern is accidentally detected at the position where the alignment correction pattern should be detected originally.
Or if the image formation speed increases, a part of the alignment correction pattern is not detected properly, and skipping of detection of the correction pattern may arise.
For this reason, as a result, failure in the color gap correction operation or incorrect correction of the amount of color gap may arise. And there is the problem that the quality of the output image will deteriorate.
The main cause of the above problems is that the difference between the blade curling prevention pattern and the alignment correction pattern is very small. Thus, a technically conceivable countermeasure to be taken to eliminate the main cause of the above problems is to widen the difference between these correction patterns.
However, taking such countermeasures is in contradiction with the demand for accelerating the image formation speed, and it will not be a realistic solution to the above problems.